An external screw member includes a head, a shank, a parallel threaded portion, a tapered threaded portion, a screw thread, a convex portion and a screw driving side end face of the convex portion. The convex portion protruding more radially outward than the crest of the screw thread is formed in at least one of the parallel threaded portion and the tapered threaded portion over the tapered threaded portion and the parallel threaded portion. The screw driving side end face of the convex portion is configured to form an inclined plane which gradually rises from a root position of the end face at the side of the crest of the screw thread toward a crest of the convex portion in a direction opposite to a screw driving direction of the screw thread to reach the crest of the convex portion.